Production of solvents



May 25 1943 J. E.y HARVEY, JR 2,319,988

PRODUCTION OF SOLVENTS Filed Aug'. 14, 1940 Patented May 25, 1943 UNITEDSTATES PATENT OFFICE PRODUCTION OF SOLVENTS Application August 14, 1940,serial No. 352,669

1 Claim.

The present invention relates to the production of valuable liquids fromtars and fractions thereof, crude and/or refined.

An object of the present invention is the subjection of tars andfractions thereof, crude 'and/ or rei-ined, to the action of hydrogen instep-wise manner, whereby to provide refined solvents of increasedsolvency and boiling range.

A further object of the present invention is the production of refinedsolvents of lowered corrosivity, the characteristics of which are, amongother things, dependent upon hydrogen supply, as hereafter explained.

Other objects of the present invention will be apparent from thefollowing disclosures.

Suitable starting materials of the present invention include tars andfractions thereof of aromatic content derived' from coal and petroleumand gas or gases of carbon content, as for instance coke oven tar, watergas tar, gas house tar, and tars of aromatic content in general, tarsproduced by cracking hydrocarbons; tars resulting from the action ofhydrogen on hydrocarbons; tars resulting from polymerization; highboiling aromatic extracts of carbonaceous substances; high boilinghydrocarbons of 'aromatic content having olenic and/or naphtheniccontent.

Especially attractive as starting material is high temperature coke oventar and fractions thereof which is available in large quantities at lowprices.

The present invention may be viewed broadly as a process for theproduction of refined solvents of lowered corrosivity by subjecting thestarting material, in step-wise manner, to the controlled action ofhydrogen whereby to produce said solvents having increased boilingpoints and enhanced solvency.

The invention will be understood from the following description ofillustrative steps comprising various methods of securing the objects ofthe invention, when read in connection with the accompanying drawingwherein the ligure is a diagrammatic sketch of an apparatus for carryingout a form of the process of the invention and wherein the nature of thestep carried out in each chamber and the contents thereof are indicatedby legend.

Example 1.-A sulfur bearing coal tar creosote, characterized by inexcess of 1% coke residue, a specic gravityof in the order of 1.05, andsubstantially 215% residue abovel 355 C. is subjected to the action ofhydrogen at 375 C. and 200 atmospheres pressure whereby to lower sulfurcontent, thereby lowering corrosivity, at least providing for loweredcorrosivity in the finished material as hereinafter described, the whileinducing no substantial percentage of low boiling ends. The creosote oflowered sulfur content is passed in liquid phase through a high pressurereaction .s no

vessel while simultaneously fnowingl, hydrogen therewith in the presenceof a molybdenum oxide catalyst at a temperature of 400 C. and 250atmospheres pressure. The time of contact is one hour and the ow of gas15,000 cubic feet per barrel refined creosote. The beneficiated creosoteupon inspection will be found to have a lowered boiling range, specificgravity and viscosity. Solvency in some of the lower fractions of thebeneficiated creosote will be a lowered quantity as compared to solventsextant of a comparable boiling range.

The beneciated material is stripped to an upper limit of 300 C. and thedistillate is passed through a high pressure reactor at 455 C. and 200atmospheres pressure while contacting a molybdenum oxide catalyst. Theflow of hydrogen is controlled at 3000 cubic feet per barrel materialthereby inducing a solvent having, as compared to the intermediatestarting material, increased boiling points and increased solvency.

The solvent so produced may be fractionated to provide refined solventsof lowered corrosivity of any boiling range within the limitations ofthe nally processed material, as for instance:

Degrees centigrade Benzol '78-120 Toluol 1GO-150 Hi-flash naphtha150-200 Heavy naphtha 150-290 Plasticizers i60-360 or others.

VThe rened solvents of lowered corrosivity serve as substitutes for thecommercial solvents noted.

In the foregoing examples, it will be noted that the present process`provides a method for contacting the starting material with hydrogenwhereby to lower sulfur content, thereafter, contacting the material oflowered sulfur content with hydrogen while contacting an oxide catalystwhereby to produce an intermediate product of lowered solvency, specicgravity, boiling range and viscosity; stripping from the beneiiciatedmaterial a fraction thereof and subjecting at least a portion of thedistillate to the controlled action of hydrogen whereby to enhancesolvency and increase boiling points thus providing the refined solventof lowered corrosivity of the present invention.

Looked at in one manner, the present process provides a method fortreating sulfur bearing ters of aromatic content, and fractions thereof,with hydrogen in step-wise manner whereby to produce refined solvents oflowered corrosivity, said solvents being characterized by increasedsolvency and boiling points when compared to the intermediate parentmaterial, as above disclosed.

of hydrogen depolymerizes, at least to a degree, said molecularcomplexes contained in the starting material.

The depolymerized or partially depolymerized tar or fractions thereof oflowered sulfur content is then stripped of a percentage of its newly in-The aforenamed step-wise action of hydrogen ring multiplicities of greatthermal susceptibility. Example 2 A sulfur containing coal tar,

`high boilers characterized by the presence of specific gravity 1.1641,a coke residue in excess of 5%, and in excess of 35% boiling at 355 C.is subjectedto the Aactionof hydrogen at 360 C. and 200 atmospherespressure for such a length of time as to lower sulfur content. The coaltar of lowered sulfur content is passed in liquid phase through a highpressure reaction chamber while simultaneously flowing hydrogentherewith at a pressure of 300 atmospheres and a temperature of 420 C.Time of contact is one hour, catalyst vanadium oxide, and flow ofhydrogen `12,000 cubic feet per barrel feed stock. The thus treated coaltar is found to have an overall lowered specific gravity, viscosity andcoke residue, and in some of its fractional parts a lowered solvency ascompared to solvents extant. The beneflciated tar is then stripped to anupper limit of 360 C. and the distillate subjected to the action of a owof hydrogen at 450 C. and 225 atmospheres pressure, withV the time ofcontact and gas flow so controlled as to increase boiling points andsolvency. YThe flow of gas in this instanceis chosen from between 2500and 3500 cubic feet per barrel feed stock.

Example 3,-A high boiling coal tar fraction of sulfur content, initialboiling point of substantially 250 C. is subjected to the action ofhydrogen at 375 C. and 300 atmospheres pressure for such a time as toreduce sulfur content, the while inducing no substantial percentage oflowboiling fractions. The coal tar'of reduced sulfur content is thenpassed in liquid phase through a highpressure reaction chamberY whilesimultanously owing hydrogen therethrough at a temperature of 410 C. and300 atmospheres pressure; catalyst, molybdenum oxide. Upon inspectionthe beneficiated coal tarfraction will be found to have a loweredspecific gravity, viscosity, coke residue, boiling range, and, in thecase of some fractional parts of the beneflciated material a loweredsolvency as compared to solvents extant.

Ihe beneficiated material is stripped to 290 C. and the distillatesubjected to the action of hydrogen at 450 C. and 300 atmospherespressure; flow of hydrogen 2,500 cubic feet per barrel feed and the timeso controlled as to increase boiling points and solvency. The time inthe last step maybe a fractional minute or more, as for instance severalminutes.

The residues incidental to the stripping actions aforenamed may berecycled or used as an article of commerce of enhanced value, as forinstance binders or the like.

The starting material of high carbon content, as for instance, hightemperature coke oven tar in its raw state, is characterized by such aperduced low ends whereby to provide the interjmediate parent materialof the refined solvents of lowered corrosivity said refined solventscharacterized by increase of boiling points and solvency; the residueincidental to said stripping may, because of its depolymerized orpartially depolymerized conditions serve as recycle material to the endthat conversion of the starting material in the percentage remainingnally liquid approaches volume for volume of the starting material intothe refined solvents of the present invention.

In the conversion of starting materials, partially or approaching unity,into the refined solvents of lowered corrosivity of the presentinvention temperatures as low as 300 C. may be employed; pressures aslow as 50 atmospheres may be used. However, temperatures and pressuresof an increased range provide better commercial practice. The timeelement is desirably that period which affords commercial recoveries ofthe products of, and incidental to, the present invention. Temperaturesare preferred that cause no ccking.

Gas flows are usually held in excess of 2,000 cubic feet per barrelmaterial treated, as for instance 2,500 cubic feet or above. In thestepwise application of hydrogen a few trials when using any of thestarting materials will determine the gas ow, when coordinated with theselected temperature and pressure conditions to effect saiddepolymerizing. The gas flow in this instance may be a variable quantitybecause of the varying ranges of coordinated temperature and pressurethat may be selected. When using any chosen coordination of temperatureand pressure, a few trials will readily determine the gas flow thatprovides depolymerizing conditions to the end that solvency, specificgravity, viscosity and boiling range are lowered.

Concerning the gas ow that increases boiling range and solvency, saidgas ow is held at that point that increases boiling range and solvencythus providing the refined solvent of lowered corrosivity of the presentinvention. A few trials with any of the intermediate starting materialsunder chosen coordination of temperature and pressure will readilydetermine the desirable gas ow. For a given coordination of temperatureand pressure, the gas ow in the last instance is lower than the gas flowin the preceding instance.

Using some starting materials, a gas ow of 10,000-15,000 cubic feet perbarrel, or higher, has proven satisfactory for depolymerizingconditions, and, gas flow in the order of 6,000-8,000 or lower whenincreasing solvency, and boiling points has proven satisfactory.

In the hydrogen action that reduces sulfur content, the action ofhydrogen may be effected in an autoclave or in a continuous plant, andin the event continuous practice is used, the now of gas is maintainedso as to assist in reduction of sulfur content, the while inducing nosubstantial percentage of carbon, low boiling fractions or percentagesof liquid chain structures that would preclude the provision of therefined solvents of superior solvency as stated.

By the term beneciated as used herein and in the appended claims ismeant the starting material at least once subjected to the action ofhydrogen in accordance with the present process.

After the starting tar has been subjected to depolymerizing action, thestripping step may be effected at any point selected within a wide rangeto provide a cut capable of providing, after further processing,substitutesI for the boiling range or ranges of benzol, toluol, xylol,naphthas, and/or plasticizers.

Thus, the depolymerized starting material may be cut according to theneed at hand, said cut being then subjected to the action of hydrogenthat increases solvency and boiling points.

The catalysts of the present invention are oxides; as for instanceoxides of metals of the 6th and 8th periodic groups; the oxides of othergroups may be used, however, diflicultly reducible oxides are preferred.The catalyst in any form may be employed, as for instance pellets,comminuted, supported on carriers or the like.

If desired, comminuted catalysts may be used in the hydrogen stepcharacterized by depolymerization; and in the step characterized bysolvency increase, a rigid catalyst may be used.

By the term multiplicity of rings, high molecular complexes andpolymerized products are meant high boiling fractions of aromaticcontent, a portion of which at least may be viewed as ring multiples; orsaid terms, any or all, may be used to describe high boiling fractionsof the starting material which because of high carbon content areespecially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting material to theprocess of the present invention, it may be desirable prior to thedepolymerizing step, or the sulfur reduction step, to at least partiallydepolymerize the molecular complexes by use of a solvent. Said solventmay be added in a small amount, or up to volume for volume or more maybe used. Refractory solvents may be desirable, but others moresusceptible to the reactions inherent in and to the present process areusable.

Concerning solvents, it may be said that tar itself, as for instancehigh temperature coke oven tar, is constituted of high molecularcomplexes dissolved, cut back or depolymerized with a solvent, saidsolvent being the .lower boiling fractions of said tar.

The action of hydrogen as aforestated may be eifected in one or morecycles or chambers, with or without releasing the pressure and with orwithout variation of process controls, including changes in eithertemperature, pressure and/or gas ow.

Various modes of practicing the present invention are possible; forinstance the depolymerized starting material may be stripped as forinstance by gas movement; the low ends thus stripped may then, with orwithout releasing pressure, be subjected to the further action ofhydrogen that increases solvency and boiling points. Or the desiredstripped material may be obtained by partial release of pressure whichwould correspond to the fractional recovery desired or predetermined.

The process may be practiced in an autoclave and/or a single highpressure reaction chamber, a series thereof, a parallelism thereof,including a multiplicity thereof.

The refined solvent of the present invention characterized by loweredcorrosivity and superior solvency may, as aforestated, be fractionatedto provide solvents and/or plasticizers of various boiling ranges, andin the instance Where solvents are processed from a deep cut on thedepolymerized material, the highest boiling fraction thereof may serveas a substitute for certain plasticizers.

In the first cycle of hydrogen action that reduces sulfur content, saidreduction of sulfur may be accomplished in the presence of a catalyst.Catalysts effective in the presence of hydrogen are usable, as forinstance the oxides and/or suliides of molybdenum, vanadium, uranium,cobalt, tin, manganese, tungsten, or the like.

In the disclosures herein made the removing of low boiling fractions bygas movement or pressure release is considered the equivalent ofdistillation.

When reference is made to high molecular complexes contained in thestarting material, and when the starting material contains low boilingfractions that are not considered high molecular complexes, it is ofcourse obvious that the high molecular complexes contained in thestarting material are to a certain extent depolymerized by the solventpresent.

Starting materials of the present process also include tars of aromaticcontent from which low boiling fractions have been removed, as forinstance tars from which solvent oils have been removed. Viewed broadly,the starting materials of the present process are tars of aromaticcontent, fractions of said tar more viscous than the starting materialdue to removal of low boiling fractions, high boiling fractions andpitches.

It will be seen that by reduction of sulfur content of the materialunder treatment during any stage of hydrogen action, the oxide catalystused during subsequent stages is at least partially protected from theeffect of the sulfur.

Minor changes may be made Within the scope of the appended claim withoutdeparting fro the spirit of the invention.

I claim:

In the production of solvents from a mixture of sulfur bearing hightemperature coal tar fractions, the process which comprises: subjectingsaid tar fractions to the action of hydrogen with time, temperature andpressure so controlled as to reduce sulfur content; subjecting said tarfractions of lowered sulfur content to the action of a relatively highflow of hydrogen whilst contacting an oxide catalyst, said hydrogen owbeing selected from the range above 10,000 cubic feet per barrelmaterial treated, at a pressure of at least about 250 atmospheres, and atemperature of at least 400 C.; carrying on the process for such alength of time as to provide a material of lowered specific gravity andviscosity; stripping low boiling fractions from the beneiiciatedmaterial; and increasing the boiling points of at least a chosen portionof said stripped fractions by subjecting same to the action of arelatively low flow of hydrogen not in excess of about 8,000 cubic feetper barrel material treated whilst maintaining a pressure andtemperature not substantially lower than about 200 atmospheres and 450C., respectively, to produce a solvent.

JACQUELIN E. HARVEY, JR.

